// based on http://sourceforge.net/projects/libmd5-rfc/
/*
  Independent implementation of MD5 (RFC 1321).

  This code implements the MD5 Algorithm defined in RFC 1321, whose
  text is available at
	http://www.ietf.org/rfc/rfc1321.txt
  The code is derived from the text of the RFC, including the test suite
  (section A.5) but excluding the rest of Appendix A.  It does not include
  any code or documentation that is identified in the RFC as being
  copyrighted.

  The original and principal author of md5.c is L. Peter Deutsch
  <ghost@aladdin.com>.  Other authors are noted in the change history
  that follows (in reverse chronological order):

  2002-04-13 lpd Clarified derivation from RFC 1321; now handles byte order
	either statically or dynamically; added missing #include <string.h>
	in library.
  2002-03-11 lpd Corrected argument list for main(), and added int return
	type, in test program and T value program.
  2002-02-21 lpd Added missing #include <stdio.h> in test program.
  2000-07-03 lpd Patched to eliminate warnings about "constant is
	unsigned in ANSI C, signed in traditional"; made test program
	self-checking.
  1999-11-04 lpd Edited comments slightly for automatic TOC extraction.
  1999-10-18 lpd Fixed typo in header comment (ansi2knr rather than md5).
  1999-05-03 lpd Original version.
 */

#include "md5.h"
#include <string.h>

#undef BYTE_ORDER	/* 1 = big-endian, -1 = little-endian, 0 = unknown */
#ifdef ARCH_IS_BIG_ENDIAN
#  define BYTE_ORDER (ARCH_IS_BIG_ENDIAN ? 1 : -1)
#else
#  define BYTE_ORDER 0
#endif

#define T_MASK ((md5_word_t)~0)
#define T1  0xd76aa478 // (T_MASK ^ 0x28955b87)
#define T2  0xe8c7b756 // (T_MASK ^ 0x173848a9)
#define T3  0x242070db
#define T4  0xc1bdceee // (T_MASK ^ 0x3e423111)
#define T5  0xf57c0faf // (T_MASK ^ 0x0a83f050)
#define T6  0x4787c62a
#define T7  0xa8304613 // (T_MASK ^ 0x57cfb9ec)
#define T8  0xfd469501 // (T_MASK ^ 0x02b96afe)
#define T9  0x698098d8
#define T10 0x8b44f7af // (T_MASK ^ 0x74bb0850)
#define T11 0xffff5bb1 // (T_MASK ^ 0x0000a44e)
#define T12 0x895cd7be // (T_MASK ^ 0x76a32841)
#define T13 0x6b901122
#define T14 0xfd987193 // (T_MASK ^ 0x02678e6c)
#define T15 0xa679438e // (T_MASK ^ 0x5986bc71)
#define T16 0x49b40821
#define T17 0xf61e2562 // (T_MASK ^ 0x09e1da9d)
#define T18 0xc040b340 // (T_MASK ^ 0x3fbf4cbf)
#define T19 0x265e5a51
#define T20 0xe9b6c7aa // (T_MASK ^ 0x16493855)
#define T21 0xd62f105d // (T_MASK ^ 0x29d0efa2)
#define T22 0x02441453
#define T23 0xd8a1e681 // (T_MASK ^ 0x275e197e)
#define T24 0xe7d3fbc8 // (T_MASK ^ 0x182c0437)
#define T25 0x21e1cde6
#define T26 0xc33707d6 // (T_MASK ^ 0x3cc8f829)
#define T27 0xf4d50d87 // (T_MASK ^ 0x0b2af278)
#define T28 0x455a14ed
#define T29 0xa9e3e905 // (T_MASK ^ 0x561c16fa)
#define T30 0xfcefa3f8 // (T_MASK ^ 0x03105c07)
#define T31 0x676f02d9
#define T32 0x8d2a4c8a // (T_MASK ^ 0x72d5b375)
#define T33 0xfffa3942 // (T_MASK ^ 0x0005c6bd)
#define T34 0x8771f681 // (T_MASK ^ 0x788e097e)
#define T35 0x6d9d6122
#define T36 0xfde5380c // (T_MASK ^ 0x021ac7f3)
#define T37 0xa4beea44 // (T_MASK ^ 0x5b4115bb)
#define T38 0x4bdecfa9
#define T39 0xf6bb4b60 // (T_MASK ^ 0x0944b49f)
#define T40 0xbebfbc70 // (T_MASK ^ 0x4140438f)
#define T41 0x289b7ec6
#define T42 0xeaa127fa // (T_MASK ^ 0x155ed805)
#define T43 0xd4ef3085 // (T_MASK ^ 0x2b10cf7a)
#define T44 0x04881d05
#define T45 0xd9d4d039 // (T_MASK ^ 0x262b2fc6)
#define T46 0xe6db99e5 // (T_MASK ^ 0x1924661a)
#define T47 0x1fa27cf8
#define T48 0xc4ac5665 // (T_MASK ^ 0x3b53a99a)
#define T49 0xf4292244 // (T_MASK ^ 0x0bd6ddbb)
#define T50 0x432aff97
#define T51 0xab9423a7 // (T_MASK ^ 0x546bdc58)
#define T52 0xfc93a039 // (T_MASK ^ 0x036c5fc6)
#define T53 0x655b59c3
#define T54 0x8f0ccc92 // (T_MASK ^ 0x70f3336d)
#define T55 0xffeff47d // (T_MASK ^ 0x00100b82)
#define T56 0x85845dd1 // (T_MASK ^ 0x7a7ba22e)
#define T57 0x6fa87e4f
#define T58 0xfe2ce6e0 // (T_MASK ^ 0x01d3191f)
#define T59 0xa3014314 // (T_MASK ^ 0x5cfebceb)
#define T60 0x4e0811a1
#define T61 0xf7537e82 // (T_MASK ^ 0x08ac817d)
#define T62 0xbd3af235 // (T_MASK ^ 0x42c50dca)
#define T63 0x2ad7d2bb
#define T64 0xeb86d391 // (T_MASK ^ 0x14792c6e)


void MD5::process(const md5_byte_t data[64])
{
	md5_word_t
		a = m_ms.abcd[0], b = m_ms.abcd[1],
		c = m_ms.abcd[2], d = m_ms.abcd[3];
	md5_word_t t;

#if BYTE_ORDER > 0
	/* Define storage only for big-endian CPUs. */
	md5_word_t X[16];
#else
	/* Define storage for little-endian or both types of CPUs. */
	md5_word_t xbuf[16];
	const md5_word_t* X;
#endif

#if BYTE_ORDER == 0
	/* Determine dynamically whether this is a big-endian or little-endian machine, since we can use a more efficient algorithm on the latter. */
	static const int w = 1;

	if( *((const md5_byte_t *)&w) ) /* dynamic little-endian */
#endif
#if BYTE_ORDER <= 0		/* little-endian */
	{
		/* On little-endian machines, we can process properly aligned data without copying it. */
		if( ((data - (const md5_byte_t*)NULL) & 3) == 0 )
		{
			/* data are properly aligned */
			X = (const md5_word_t*)data;
		}
		else
		{
			/* not aligned */
			memcpy(xbuf, data, 64);
			X = xbuf;
		}
	}
#endif
#if BYTE_ORDER == 0
	else			/* dynamic big-endian */
#endif
#if BYTE_ORDER >= 0		/* big-endian */
	{
		/* On big-endian machines, we must arrange the bytes in the right order. */
		const md5_byte_t* xp = data;

#  if BYTE_ORDER == 0
		X = xbuf;		/* (dynamic only) */
#  else
#	define xbuf X		/* (static only) */
#  endif
		for( int i = 0; i < 16; ++i, xp += 4 )
			xbuf[i] = xp[0] + (xp[1] << 8) + (xp[2] << 16) + (xp[3] << 24);
	}
#endif

#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32 - (n))))

	/* Round 1. */
	/* Let [abcd k s i] denote the operation a = b + ((a + F(b,c,d) + X[k] + T[i]) <<< s). */
#define F(x, y, z) (((x) & (y)) | (~(x) & (z)))
#define SET(a, b, c, d, k, s, Ti) t = a + F(b,c,d) + X[k] + Ti; a = ROTATE_LEFT(t, s) + b
	/* Do the following 16 operations. */
	SET(a, b, c, d,  0,  7,  T1);
	SET(d, a, b, c,  1, 12,  T2);
	SET(c, d, a, b,  2, 17,  T3);
	SET(b, c, d, a,  3, 22,  T4);
	SET(a, b, c, d,  4,  7,  T5);
	SET(d, a, b, c,  5, 12,  T6);
	SET(c, d, a, b,  6, 17,  T7);
	SET(b, c, d, a,  7, 22,  T8);
	SET(a, b, c, d,  8,  7,  T9);
	SET(d, a, b, c,  9, 12, T10);
	SET(c, d, a, b, 10, 17, T11);
	SET(b, c, d, a, 11, 22, T12);
	SET(a, b, c, d, 12,  7, T13);
	SET(d, a, b, c, 13, 12, T14);
	SET(c, d, a, b, 14, 17, T15);
	SET(b, c, d, a, 15, 22, T16);
#undef SET

	/* Round 2. */
	/* Let [abcd k s i] denote the operation a = b + ((a + G(b,c,d) + X[k] + T[i]) <<< s). */
#define G(x, y, z) (((x) & (z)) | ((y) & ~(z)))
#define SET(a, b, c, d, k, s, Ti) t = a + G(b,c,d) + X[k] + Ti; a = ROTATE_LEFT(t, s) + b
	/* Do the following 16 operations. */
	SET(a, b, c, d,  1,  5, T17);
	SET(d, a, b, c,  6,  9, T18);
	SET(c, d, a, b, 11, 14, T19);
	SET(b, c, d, a,  0, 20, T20);
	SET(a, b, c, d,  5,  5, T21);
	SET(d, a, b, c, 10,  9, T22);
	SET(c, d, a, b, 15, 14, T23);
	SET(b, c, d, a,  4, 20, T24);
	SET(a, b, c, d,  9,  5, T25);
	SET(d, a, b, c, 14,  9, T26);
	SET(c, d, a, b,  3, 14, T27);
	SET(b, c, d, a,  8, 20, T28);
	SET(a, b, c, d, 13,  5, T29);
	SET(d, a, b, c,  2,  9, T30);
	SET(c, d, a, b,  7, 14, T31);
	SET(b, c, d, a, 12, 20, T32);
#undef SET

	/* Round 3. */
	/* Let [abcd k s t] denote the operation a = b + ((a + H(b,c,d) + X[k] + T[i]) <<< s). */
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define SET(a, b, c, d, k, s, Ti) t = a + H(b,c,d) + X[k] + Ti; a = ROTATE_LEFT(t, s) + b
	/* Do the following 16 operations. */
	SET(a, b, c, d,  5,  4, T33);
	SET(d, a, b, c,  8, 11, T34);
	SET(c, d, a, b, 11, 16, T35);
	SET(b, c, d, a, 14, 23, T36);
	SET(a, b, c, d,  1,  4, T37);
	SET(d, a, b, c,  4, 11, T38);
	SET(c, d, a, b,  7, 16, T39);
	SET(b, c, d, a, 10, 23, T40);
	SET(a, b, c, d, 13,  4, T41);
	SET(d, a, b, c,  0, 11, T42);
	SET(c, d, a, b,  3, 16, T43);
	SET(b, c, d, a,  6, 23, T44);
	SET(a, b, c, d,  9,  4, T45);
	SET(d, a, b, c, 12, 11, T46);
	SET(c, d, a, b, 15, 16, T47);
	SET(b, c, d, a,  2, 23, T48);
#undef SET

	/* Round 4. */
	/* Let [abcd k s t] denote the operation a = b + ((a + I(b,c,d) + X[k] + T[i]) <<< s). */
#define I(x, y, z) ((y) ^ ((x) | ~(z)))
#define SET(a, b, c, d, k, s, Ti) t = a + I(b,c,d) + X[k] + Ti; a = ROTATE_LEFT(t, s) + b
	/* Do the following 16 operations. */
	SET(a, b, c, d,  0,  6, T49);
	SET(d, a, b, c,  7, 10, T50);
	SET(c, d, a, b, 14, 15, T51);
	SET(b, c, d, a,  5, 21, T52);
	SET(a, b, c, d, 12,  6, T53);
	SET(d, a, b, c,  3, 10, T54);
	SET(c, d, a, b, 10, 15, T55);
	SET(b, c, d, a,  1, 21, T56);
	SET(a, b, c, d,  8,  6, T57);
	SET(d, a, b, c, 15, 10, T58);
	SET(c, d, a, b,  6, 15, T59);
	SET(b, c, d, a, 13, 21, T60);
	SET(a, b, c, d,  4,  6, T61);
	SET(d, a, b, c, 11, 10, T62);
	SET(c, d, a, b,  2, 15, T63);
	SET(b, c, d, a,  9, 21, T64);
#undef SET

	/* Then perform the following additions. (That is increment each of the four registers by the value it had before this block was started.) */
	m_ms.abcd[0] += a;
	m_ms.abcd[1] += b;
	m_ms.abcd[2] += c;
	m_ms.abcd[3] += d;
}


void MD5::init()
{
	m_ms.count[0] = 0;
	m_ms.count[1] = 0;
	m_ms.abcd[0] = 0x67452301;
	m_ms.abcd[1] = 0xEFCDAB89; // T_MASK ^ 0x10325476
	m_ms.abcd[2] = 0x98BADCFE; // T_MASK ^ 0x67452301
	m_ms.abcd[3] = 0x10325476;
}


void MD5::append(const md5_byte_t* data, int nbytes)
{
	const md5_byte_t* p = data;
	int left = nbytes;
	int offset = (m_ms.count[0] >> 3) % 64; // number of bytes already in work buffer

	if( nbytes <= 0 )
		return;

	/* Update the message length. */
	md5_word_t nbits = (md5_word_t)(nbytes << 3);
	m_ms.count[0] += nbits;
	m_ms.count[1] += nbytes >> 29;
	if( m_ms.count[0] < nbits ) // wraparound
		m_ms.count[1]++; // carry bit

	/* Process an initial partial block. */
	if( offset != 0 )
	{
		int copy = min(left, 64 - offset);
		memcpy(m_ms.buf + offset, p, copy);

		if( offset + copy < 64 )
			return; // not enough data to form a full block

		p += copy;
		left -= copy;
		this->MD5::process(m_ms.buf);
	}

	/* Process full blocks. */
	for( ; left >= 64; p += 64, left -= 64 )
		this->MD5::process(p);

	/* Process a final partial block. */
	if( left != 0 )
		memcpy(m_ms.buf, p, left);
}


void MD5::finish(md5_byte_t digest[16])
{
	md5_byte_t data[8];

	/* Save the length before padding. */
	for( int i = 0; i < 8; ++i )
		data[i] = (md5_byte_t)(m_ms.count[i >> 2] >> ((i & 3) << 3));

	/* Pad to 56 bytes mod 64. */
	static md5_byte_t pad[64] = { 0x80 };
	this->MD5::append(pad, ((64 - (m_ms.count[0] >> 3) - 8 - 1) % 64) + 1);

	/* Append the length. */
	this->MD5::append(data, 8);

	/* Output digest. */
	for( int i = 0; i < 16; ++i )
		digest[i] = (md5_byte_t)(m_ms.abcd[i >> 2] >> ((i & 3) << 3));
}


// guessed
void MD5::result(const md5_byte_t* data, int nbytes, md5_byte_t digest[16])
{
	this->init();
	this->append(data, nbytes);
	this->finish(digest);
}
